The Solar Heat Gain Coefficient (SHGC) is the absorption of solar energy by structures like windows that increases room temperature. The SHGC is used to determine the energy efficiency of windows. The SHGC warms the room during winter but leads to overheating of the room in summer. Therefore, glass manufacturing companies try to achieve an ideal SHGC by applying tints and coats to the glass. SHGC measurements range from 0 to 1, with zero being the lowest heat absorbed by the window and one being the maximum heat absorbed by the window. The climate, window orientation, and shades like trees help determine the right SHGC for the window.

Why is SHGC Important?

The solar heat gain coefficient has great significance. Firstly, it helps determine the energy efficiency of windows before installation. Additionally, a high SHGC heats the house during winter and reduces the heating energy. SHGC also helps window and door manufacturers to make informed decisions on the type of doors or windows. Ultimately, determining the ideal SHGC for your home will help you save on cooling and heating. Selecting the right SHGC for your home leads to a more comfortable home.

What is the Difference Between U-Factor and SHGC?

The U-factor is also called the U-value. It is the amount of heat in a room transmitted through the window, wall, or door. A lower U-factor provides the space with better insulation. The U-factor and SHGC both determine the energy efficiency of a window.

Professionals measure the U-factor with a number between 0.20 and 1.20. A lower number indicates good insulation. On the other hand, the SHGC measures the heat that radiates through the window. The SHGC is estimated between 0 and 1, with 1 indicating a high level of heat gain. Achieving optimal levels of U-factor and SHGC is essential in achieving comfort in your home.

A low U-factor is ideal for areas with a cool climate as it helps retain the heat in houses. Conversely, a high SHGC is suitable for places with cold temperatures as it allows the sun to insulate your home. Factors that determine the ideal U-factor and SHGC for your home include the climate, window orientation, and occupants' preferences. Considering both the U-factor and SHGC is essential when selecting the windows and doors for your home.

How Can the SHGC Value Be Reduced?

A high level of SHGC translates into more heat transmission in the building. High SHGC levels result in discomfort in the home. Not only that, but it significantly increases the cooling cost in summer. You can reduce SHGC in the following ways:

● Using low emissivity heat glass (Low-E glass). Low-e-glass is glass with a coating to reduce solar radiation that gets in the building while allowing sufficient light into the building.

● Using shading devices: shading devices block direct sunlight from penetrating the building. They include materials like overhangs, exterior shades, and trees.

● Purchase window films: you can install window films on your windows to reduce solar radiation entering the building.

● Use reflective coatings on your window: reflective coatings reflect solar radiation and regulate the amount of heat in the building.

● Select your window orientation carefully: Windows facing the north or south reduce sunlight entering the building. On the other hand, windows facing the east or west receive much more sunlight.

● Plant trees and other vegetation: Trees and plants provide adequate shade that blocks excessive sunlight from entering the building.

● Use interior shading: interior shading comprises shades, blinds, and curtains. They block solar radiation and are effective in reducing SHGC.

How Do These Values Determine Which Window or Door to Install

SHGC and U-factor are essential factors to consider when purchasing windows and doors for your home. Factors like the building orientation, the climate, and the energy efficiency of the building determine the kind of windows and doors you select.

Windows and doors with low U-factor and SHGC are more expensive but are energy efficient. They are a long-term investment as they save on energy bills over time. For instance, windows with a fiberglass frame are more insulative and efficient for use in areas with a low SHGC. On the other hand, areas with high levels of SHGC require windows with low emissivity heat glass to reduce the SHGC.

Similarly, windows with double and triple-glazing are more energy efficient as they have a U-value of 0.3 and lower. Doors and windows with high insulation are ideal for areas with a low U-factor and vice-versa. Areas with scorching climates require windows or doors with lower SHGC but a higher U- factor to prevent excessive heat gain and reduce cooling costs.

Therefore, when selecting windows and doors for your home, it is essential to consider the ones with a good U-factor and SHGC rating. Also, you should purchase doors and windows that suit the specific weather conditions of where you live. Additionally, it would help if you optimized doors and windows to work your building. Ultimately choosing the right windows and doors goes a long way in improving energy efficiency and reducing heating and cooling costs.


SHGC measures the amount of solar energy that enters the home through the door, wall, or window. It is estimated with numbers between 0 and 1, with o representing low heat gain and 1 representing more heat gain. U-factor, on the other hand, is the amount of heat transmitted through the door or windows. The U-factor or U-value is estimated with numbers between 0.20 and 1.20, with the lower numbers indicating good insulation of the window or doors.

A high SHGC is optimal for low-climate areas as it helps insulate the home. However, a high SHGC level is not suitable for areas with hot climates as it increases the heat leading to an increase in the cooling bill. Getting energy-efficient windows and doors will help you cut the cost of energy bills.

It is paramount to check the SHGC and U-value rating on doors and windows before purchasing them to make the right decision for your home. Most importantly, it would help to buy windows and doors suitable for the weather condition and building orientation of your home. Additionally, it would be best to consult a professional to ensure that your doors and windows meet the required energy efficiency standards.